Aharon HaKohen was reluctant to approach the Mizbayach, because he was ashamed of his role in the creation of the eigal ha’zahav, Golden Calf. Moshe Rabbeinu attempted to assuage his perceived guilt and apparent shame, saying, “Why are you embarrassed? It is for this reason that Hashem chose you to be the Kohen Gadol, High Priest.” Simply, this means that Hashem chose Aharon to fill the position; therefore, he must execute the service. It is not an optional, arbitrary position. It is mandatory. Alternatively, the Degel Machane Efraim explains that it was specifically Aharon’s sense of shame and inadequacy that catalyzed Hashem choosing him for the position of Kohen Gadol. A leader requires utmost humility in order to be able to lead properly. One who is filled with himself has no room left for those in his care.
The Zera Shimshon focuses on Moshe’s rejoinder to Aharon: L’kach nivcharta, “It is for this that you were chosen.” He explains that, quite possibly, Aharon permitted/facilitated the creation of the Golden Calf, because he was acutely aware of what coursed through the minds of the people: they wanted to worship avodah zarah, an idol. This had been their pastime in Egypt. This is what they were accustomed to doing. The idea of worshipping Hashem exclusively was novel to them. The problem was that unless they acted and carried out what was presently only in their minds, they would never properly repent. One repents what he has done. One does not repent inappropriate thoughts. In the sinner’s mind, he has not performed an inappropriate act. Imagination is not a sin. This might be true, but one thing is for certain: when one thinks about something long enough, he eventually takes action. The “germ” is present; the infection is dormant, waiting for its opportunity to destroy the body.
Thus, when the Golden Calf actually became reality, the nation passed from the realm of sinful thought to sinful deed. Now they could do teshuvah, because they had actually sinned. They saw with their own eyes the evil they had wrought. Aharon knew that they would now regret their actions and perform true teshuvah. Thus, his action in creating the Golden Calf catalyzed their shame which would segue into teshuvah.
The Zera Shimshon cites Chazal (Berachos 12b), “Anyone who sins and is ashamed of his actions is forgiven for his sins.” Shame mitigates the sin. The humbling consequences of sin, the shame it brings, and the choices we make to relieve our uneasiness (and in some instances – agony) distresses us up to the point that if we accept our guilt, we will repent. The chagrin we experience transforms into remorse over our sinful action, prompting a resolve to never act in such a manner again. This is true teshuvah.
We now understand what Moshe meant when he asked Aharon: “Why are you embarrassed? Your shame concerning your involvement in the Golden Calf debacle presents itself as a form of guilt. Why do you feel a sense of guilt when you did nothing wrong? On the contrary – your act of creating the Golden Calf brought the nation to feel shame, which catalyzed their teshuvah. Indeed, this is specifically the reason that you were chosen to be the High Priest.
“Hashem repays a person middah k’neged middah, measure for measure. Just as you ‘assisted’ Klal Yisrael in achieving the plateau of teshuvah, so, too, will your גescendants, the Kohanim, serve as the nation’s spiritual mentors, and also as agents to intercede on their behalf in the Bais Hamikdash, thereby facilitating their ultimate teshuvah via their reconnecting with Hashem.”